Off brand lenses – good or bad?

OK, let’s get this out of the way – I shoot Nikon, and I have very little (almost zero) knowledge of the Canon lens line up, and even less for other manufacturers, so my apologies to any non-Nikon shooters reading this, as it may well have zero relevance to you!

When I first started with a DSLR, it came with a kit lens. Being a D70, this kit lens was the Nikon 18-70mm.
When I upgraded to the D90 I had a 10-24mm, 50mm f/1.8 and the 70-300mm VR, all Nikon glass.

I decided then that I would stick with just Nikon (Well, Nikkor to be precise) glass for my Nikon camera – better quality, better resale value, guaranteed compatability etc.

This however didn’t last long, as a friend was selling a Sigma 17-70mm f/2.8-4.0 zoom, which I bought. I found it a great lens, very sharp and great in low light, with a great range for a travel lens. And it was cheap, oh so cheap! £120 used, versus around £1000 for the Nikon 17-55mm f/2.8.
This was followed by a Tokina 10-17mm fisheye zoom, which became my go-to wide angle lens for underwater photography. Nobody else at the time made a fisheye zoom.
Recently, I have bought the Tamron 150-600mm, with a view to replacing my Nikon 80-400mm (the new version). Nikon does not offer a zoom that gets out to 600mm, it’s less than half the price of the Nikon 80-400mm, and first impressions are that the lens is as sharp at 550mm as the Nikon is at 400mm.

As with everything in life, there are pros and cons with using an off brand lens, but for someone like myself who doesn’t earn all of their money from photography, good value is also important, and I feel that if you can look past their shortcomings, then third part lenses are a great option.

At the end of the day, for me, as long as I can get a nice sharp image then more pounds in my pocket means more trips to nice places. One of the below images was shot on a £2000 lens, the other on one that was £750 – can you really tell which was which?
PS – the reason for 2 bird photos? They usually need long focal lengths, and feather detail shows up a lack of sharpness quite well.